/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
 */
package com.opensource.dbhelp.dbutils.handlers;

import java.sql.ResultSet;
import java.sql.SQLException;

import com.opensource.dbhelp.dbutils.ResultSetHandler;
import com.opensource.dbhelp.dbutils.RowProcessor;

/**
 * <code>ResultSetHandler</code> implementation that converts the first <code>ResultSet</code> row into a JavaBean. This class is thread safe.
 *
 * @param <T>
 *            the target bean type
 * @see com.opensource.dbhelp.dbutils.ResultSetHandler
 */
public class BeanHandler<T> implements ResultSetHandler<T> {

	/**
	 * The Class of beans produced by this handler.
	 */
	private final Class<T> type;

	/**
	 * The RowProcessor implementation to use when converting rows into beans.
	 */
	private final RowProcessor convert;

	/**
	 * Creates a new instance of BeanHandler.
	 *
	 * @param type
	 *            The Class that objects returned from <code>handle()</code> are created from.
	 */
	public BeanHandler(Class<T> type) {
		this(type, ArrayHandler.ROW_PROCESSOR);
	}

	/**
	 * Creates a new instance of BeanHandler.
	 *
	 * @param type
	 *            The Class that objects returned from <code>handle()</code> are created from.
	 * @param convert
	 *            The <code>RowProcessor</code> implementation to use when converting rows into beans.
	 */
	public BeanHandler(Class<T> type, RowProcessor convert) {
		this.type = type;
		this.convert = convert;
	}

	/**
	 * Convert the first row of the <code>ResultSet</code> into a bean with the <code>Class</code> given in the constructor.
	 * 
	 * @param rs
	 *            <code>ResultSet</code> to process.
	 * @return An initialized JavaBean or <code>null</code> if there were no rows in the <code>ResultSet</code>.
	 * @throws java.sql.SQLException
	 *             if a database access error occurs
	 * @see com.opensource.dbhelp.dbutils.ResultSetHandler#handle(java.sql.ResultSet)
	 */
	@Override
	public T handle(ResultSet rs) throws SQLException {
		return rs.next() ? this.convert.toBean(rs, this.type) : null;
	}

}